The glass formation and crystallization studies on iron phosphate–silicate glasses

The assessment of impact of incorporation of various amount of Fe2O3 at the expense of MgO and CaO on the glassy phase formation and thermal stability exhibited in P2O5–SiO2–K2O–MgO–CaO–Fe2O3 system was carried out. The characteristic temperatures for iron phosphate–silicate glasses and glass-crystalline materials were designated from associated DSC curves. Selected samples were subjected to the process of induced crystallization, and products combined with particular exothermic effects were identified. Combination of DSC, XRD and SEM–EDS methods enabled to collect invaluable data concerning the course of crystallization of not only iron phosphate–silicate glasses subjected to the process of induced crystallization, but also glass-crystalline materials obtained directly through melt-quenched technique. The amount of particular crystalline products associated with selected devitrificates was determined via Rietveld technique. Results of the conducted study indicated that Fe2O3 addition conduces to the decrease in crystallization temperatures and thermal stability which was reflected in calculated values of ΔT and KW parameters. Concomitantly, glass with 20 mol% iron (III) oxide addition exhibited significantly improved, distinctive thermal stability among the materials in the analyzed series. The connection of crystalline phases with gradual alterations in polymerization degree of glass matrix was also established. The performed study is a contribution to the knowledge of iron phosphate glasses family and associated glass-crystalline materials.